The present invention relates generally to riding mowers having height-adjustable mower decks with motorized cutting blades. In particular, the present invention relates to a belt-drive mechanism for transferring power via a drive belt from a drive pulley wheel connected to the drive shaft of a mower engine to a deck pulley wheel associated with the mower deck.
Riding mowers with height-adjustable mower decks are capable of cutting vegetation to different heights. By adjusting the deck height, the amount of vegetation cut by the motorized cutting blades is accordingly adjusted. The cutting blades are powered by the mower engine through the use of a drive belt, which engages a drive pulley wheel and a plurality of deck pulley wheels. The drive pulley wheel is connected to the mower engine and transfers power from the engine to the drive belt. The plurality of deck pulley wheels are mounted to the deck of the mower and typically at least one of the deck pulley wheels is connected to a cutting blade via a blade shaft. In addition, typically at least one of the deck pulley wheels functions as an idler pulley wheel to provide tension to the drive belt.
This arrangement efficiently operates cutting blades when the drive pulley wheel and the deck pulley wheels rotate in a common plane. A problem may occur, however, when the height of the mower deck is adjusted because, as the mower deck is raised or lowered, the deck pulley wheels are correspondingly raised or lowered, while the position of the drive pulley wheel remains fixed. The greater the vertical displacement of the drive pulley wheel and the deck pulley wheels, the greater the angular displacement of the drive belt relative to the drive pulley wheel and the deck pulley wheels, which may increase wear on the drive belt and may throw the drive belt off the pulley wheels. To minimize these problems, most mowers having height-adjustable decks with a restricted range of mowing heights, typically between about 1.5 inches to about 4.5 inches.
An improved belt-drive mechanism for mowers with height adjustable decks is needed to reduce drive belt wear and maintain the drive belt on the pulley wheel system.